Joyce group

Dr Susan Joyce

About the Bile Research group

Our research focuses on microbial bile acid modification systems and the resulting impact on host signaling to influence host health and disease status.

Bile acids are gastrointestinal (GI) emulsifying molecules that present lipids for digestion and in doing so liberate vitamins D,E,K, and A. These molecules maintain microbial populations in check due to their chemical nature, their signatures and their spatial distribution in the GI tract. In turn, the complexity and diversity of gastrointestinal bile acids are dictated by microbial enzyme modification and bile acids are now recognised as important signaling molecules in the host. The microbe generated bile acid complexity can influence host processes (either locally or systemically) by interaction with cellular receptors -including FXR, TGR5, VDR, LXR, PPAR and SIP2- to impact on host metabolic processes such as circadian rhythm, lipid metabolism, energy metabolism, immune and intestinal homeostasis. Therefore, bile acid complexity and alterations to complexity can have an impact upon host health. In agreement, alterations to the gut microbiota that influence bile acid metabolism are correlated with a number of disease states and these include obesity, irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), colorectal cancer (CRC) and non-alcoholic liver disease (NAFLD). We are interested in characterizing bile salt and bile acid altering enzymes, their impact/s on the gut microbiota, their effects on host signaling and how these may be utilized to intervene in the disease state.